The rapid development of near-infrared (NIR) photonics promises non- invasive diagnostics, imaging, and pathological tissue characterization from economical optical measurements. However, since the scattering properties of tissues convolute re-emitted NIR signals, the extraction of biomedically pertinent information continues to remain elusive. Before the technological advances in the photonics field can substantially impact diagnostic medicine an understanding of light transport and light-tissue interaction is required. Biomedical research efforts in the Photon Migration Laboratory at Purdue University focus upon the biophysics of light transport and interactions within tissues in order to engineer appropriate approaches for non- invasive imaging and tissue spectroscopy. Specifically, measurements of photon migration in the time- and frequency- domains are developed for "photon migration imaging" (NCI-RO1CA1413-02), lifetime-based chemical sensing in tissues (NCI-R01CA67176-O1, pending), and functional/structural spectroscopic imaging on the basis of tissue optical properties (NSF-BCS- 9358254). Among the applications which drive these fundamental studies are: (i) photon migration approaches for breast cancer screening in patients who are not candidates for conventional x-ray mammography, (ii) non-invasive intratumor pO2 measurements for efficacious staging of therapeutic intervention and, (iii) identification of metabolic tissue states from measurement of endogenous and exogenous lifetimes. This Research Career Development application for support of Professor Eva M. Sevick-Muraca will facilitate the continuation of these biomedical research activities and the integration of her biomedical research into the training and teaching agendas of the Biomedical Engineering Program and the School of Chemical Engineering at Purdue University. Interdisciplinary interactions within the Purdue Veterinary School, Hillenbrand Biomedical Engineering Center, and the Indiana Medical School at the Indianapolis campus will be enhanced and insure the direction of research towards a clinically pertinent and feasible system. In the long- term, the proposed support would enable Dr. Sevick to devote efforts during the duration of the award towards the establishment of an internationally based industrial consortium for the interdisciplinary Biomedical Optics research community.